Journal $Medicinal Chemistry 0 Copyright 1988 by the American Chemical Society
March 1988
Volume 31, Number 3
Communications to the Editor Acetohydroxamic Acids as Potent, Selective, Orally Active 5-Lipoxygenase Inhibitors Sir: In the search for novel inhibitors of the 5-lipoxygenase (5-LO) pathway of arachidonic acid metabolism, we have had occasion to look a t several series of hydroxamic acids, two examples of which are described within. The 5-LO pathway leads to several compounds with extremely potent biological activities: leukotriene B4 (LTB4)has been shown1 to be a potent chemotactic agent in vivo, while the peptido leukotrienes LTC4 and LTD4are powerful bronchoconstrictors2 and lead to an increase in vascular ~ermeability.~Furthermore, elevated levels of leukotrienes have been found4in certain disease states such as asthma, rheumatoid arthritis, and psoriasis. We5 and others have developed compounds that inhibit the 5-LO or 5-LO and cyclooxygenase (CO) pathways of arachidonic acid metabolism, while the alternative approach of leukotriene antagonists has also been extensively investigated? Unfortunately, many of the compounds so far developed suffer from toxicity problems or lack of oral bioavailability. More recently, several groups have prepared analogues of arachidonic acid,' 5-HETE: and 15HETEg which contain a hydroxamic acid moiety. In these examples, the hydroxamic acid portion of the molecule is thought to bind to Fe3+at the catalytic site of the enzyme. On this basis, a number of hydroxamic acids were prepared as potential 5-LO inhibitors. Of these, compounds 1 (BW A137C), N- [4- (benzyloxy)benzyl]acetohydroxamic acid, and 2 (BW A4C), N-[(E)-3-(3-phenoxyphenyl)prop2-enyl]acetohydroxamic acid, were found to be potent, selective inhibitors of human leukocyte 5-LO (Table I) and to demonstrate significant oral bioavailability in animals. Compound 1 was prepared from the oxime of 4-(benzyl-
Table I. In Vitro Inhibition of 5-LO and CO from Human Polymorphs compd mp, "C ICSO, pM:' 5-LO co 1 121-122 0.77 f 0.16 (9)b 22 f 4 (9) 0.2-2.3' 0.14 f 0.03 (7)b 3.2 f 0.8 2 84 0.06-0.36' 4 124-125 0.05 f 0.01 (3Ib 5 f 3 (3) Homogenate5 of human polymorphs were preincubated with inhibitor (added in DMSO) for 5 min at 37 "C before initiating reaction by addition of arachidonic acid and CaClz (final concentrations 5 pM and 2 mM, respectively). After a further 5 min, incubation reaction was stopped by boiling, and LTBl and TXBz were assayed by RIA.lS bMean f SEM for (n) experiments. 'Minimum and maximum IC60(s.
-
Scheme I" ArCHO
ArCHNOH
-
ArCHzNCOCH3
I 0
-
ArCH2NCOCH3
I
OH
COCH3
1
0-
"Ar = PhCHzO 1 \
Scheme 'IIa ArCHO
-
-
Ar+COOCH3
-
Ar-CHzNHOTHP
3 Ar/\L-CH2yCOCH3
-
Ar+CH*Br
Ar/\\---CH2iH20H
-
CIAr-CHzYCOCH3
I
I
0
COCH3
OH
2
'Ar = PhO
Bray, M. A. Br. Med. Bull. 1983, 39, 249. Weiss, J. W.; Drazen, J. M.; Coles, N.; McFadden, E. R.; Weller, P. W.; Corey, E. J.; Lewis, R. A.; Austen, K. F. Science (Washington,D.C.) 1982, 216, 196. Bisgaard, H.; Kirstensen, J.; Sodengaard, J. Prostaglandins 1982,23, 801. Bray, M. A. Agents Actions 1986,19, 87. Higgs, G. A.; Flower, R. J.; Vane, J. R. Biochem. Pharmacol. 1979, 28, 1959.
Gardiner, P. J. In Drugs Affecting Leukotrienes and Lipoxygenase Products; A Potential Fulfilled? IBC Technical Services Ltd.: London, 1987; Cashman, J. R. Pharm. Res. 1985, 253. Corey, E. J.; Cashman, J. R.; Kantner, S. S.; Wright, S. W. J. Am. Chem. Soc. 1984,106, 1503. Kerdesky, F. A. J.; Holms, J. H.; Schmidt, S. P.; Dyer, R. D.; Carter, G. W. Tetrahedron Lett. 1985, 2143. Nicolaou, K. C.; Ladduwahetty, T.; Elisseou, E. M. J . Chem. Soc., Chem. Commun. 1985,1580. 0022-2623/88/1831-0499$01.50/0
0xy)benzaldehyde by reduction with sodium cyanoborohydride in acetic acid followed by in situ treatment with acetic anhydride; selective removal of the 0-acetyl group then gave 1 in high yield (Scheme I). The preparation of 2 proved somewhat more problematic; reduction of the appropriate unsaturated oxime, as above, gave the unsaturated hydroxylamine, which is unstable at the pH of the reaction medium. Although 2 could be obtained by this route, extensive purification was required and yields were low. A preferable synthesis is shown in Scheme 11. Reaction of 3-phenoxybenzaldehyde under standard conditions (pyridine, malonic acid, piperidine) gave the cinnamic acid, which was esterified, reduced (DIBAL),and converted to the (E)-allylicbromide (1:l Et20/hexane, 48% HBr). Reaction with 3 equiv of O-tetrahydropyranylhydroxylaminelo in DMF gave the 0 1988 American Chemical Society
J. Med. Chem. 1988,31, 500-503
500
monoalkylated hydroxylamine 3 together with about 10% bisalkylated product. Hydrolysis of the crude reaction mixture with concentrated HC1 in MeOH gave the deprotected hydroxylamine hydrochloride, which was purified by crystallization (EtOAc). Acetylation followed by 0-deacetylation, as above, gave 2 in good overall yield. Acetylation of 3 followed by deprotection (PPTS, MeOH) gave less pure product. Both 1 and 2 have so far been found to be devoid of toxicity problems and to be nonmutagenicl’ in the Ames Salmonella test. Furthermore, 1 and 2 selectively inhibit the ex vivo Ca2+ionophore stimulated production of LTB4 in whole rat blood for well over 6 h after a single oral dose of 50 mg/kg; compound 2, in fact, has an ED,, at 6 h of 9 mg/kg. In contrast, compound 4,which is structurally
I
+ T h e Wellcome Research Laboratories. Schering Agrochemicals Ltd.
William P. Jackson,*+Peter J. Islip,+Geoffrey Kneent Ashley Pugh,+Peter J. Watest The Wellcome Research Laboratories Langley Court, Beckenham Kent, United Kingdom BR3 3BS Schering Agrochemicals Ltd. Chesterford Park Research Station Saffron Walden, Essex, United Kingdom CBlO 1XL Received July 7, 1987
9-(trans-2’,trans -3’-Dihydroxycyclopent-4’-enyl) Derivatives of Adenine and 3-Deazaadenine: Potent Inhibitors of Bovine Liver S -Adenosylhomocysteine Hydrolase
OH 4
similar to and in vitro is equipotent with 2 shows no ex vivo activity at 6 h after 50 mg/kg orally in rats. It should be noted that 4 is structurally related to the hydroxamic acid based inhibitors recently disclosed by several other groups.12 Compound 2 has also demonstrated its ability to block the “leukotriene-dependent” anaphylactic bronchospa~ml~ in anesthetized guinea pigs in a dose-related manner. In the 6-h carrageenin sponge implant model of inflammation,14 2 selectively inhibits the formation of LTB4 over PGEz in the sponge exudates with an ED,, of 2.6 mg/kg. This inhibition was accompanied by a decrease in the number of leukocytes in the sponge exudate, but there was no direct correlation between the two values. Further extensive biological observations with compounds 1 and 2 will appear in due course.15 Thus, with the development of potent, selective, orally active inhibitors of &LO, it should be possible to determine the relevance of lipoxygenase’ products in human disease states.
Acknowledgment. We thank our biological collaborators for their dedicated support in this project. Registry No. 1, 106328-28-3; 1 (0-acetyl deriv), 106328-89-6; 2, 106328-57-8; 2 (0-acetyl deriv), 112270-90-3; 3, 112270-88-9; &LO, 80619-02-9; 4-(benzy1oxy)benzaldehyde oxime, 76193-67-4; 3-phenoxybenzaldehyde, 39515-51-0; malonic acid, 141-82-2; methyl 3-[(4-phenoxy)phenyl]propenoate,87087-33-0; 3-bromo1-[(4-phenoxy)phenyl]propene,112270-87-8; N-hydroxy-3-(4phenoxyphenyl)-2-propenaminehydrochloride, 112270-89-0. _
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(10) Warrener, R. N.; Cain, E. N. Angew. Chem., Int. Ed. Engl. 1966, 5, 511. (11) Unpublished observations from the Wellcome Biological Control Laboratories, Dartford, UK. (12) Summers, J. B.; Mazdiyasni, H.; Holms, J. H.; Ratajczyk, J. D.; Dyer, R. D.; Carter, G. W. J. Med. Chem. 1987,30, 574; Brit. UK Pat. Appl. 2183637; Eur. Pat. Appl. 0196674; U.S. Pat. Appl. 4604407; US. Pat. Appl. 4607053. Summers, J. B.; Gunn, B. P.; Mazdiyasni, H.; Goetze, A. M.; Young. P. R; Bouska, J. B.; Dyer, R. D.; Brooks, D. W. J . Med. Chem. 1987, 30, 2121. (13) Payne, A. N.; Garland, L. G.; Lees, I. W.; Salmon, J. A. Br. J. Pharmacol., in press. (14) Higgs, G. A,; Follenfant, R. L.; Garland, L. G. Br. J . Pharmacol., in press. (15) Tateson, J. E.; Randall, R. W.; Reynolds, C. H.; Jackson, W. P.: Bhattacheriee, P.; Salmon, J. A.; Garland, L. G. Br. J . Pharmacol., in press.
Sir: Neplanocin A (NpcA, Chart I), a cytotoxic, cyclopentenyl analogue of adenosine, is a naturally occurring antitumor antibiotic, which was isolated from the bacterium Ampullariella r e g ~ l a r i s . l - ~NpcA possesses antitumor activity in vivo against murine L1210 leukemia in mice2$,and antiviral activity in cell culture against vaccinia virus,6 herpes simplex-1,’ herpes simplex-2,7and vesicular stomatitis virus.’ Our laboratory has shown that NpcA is a potent, irreversible inhibitor of S-adenosylhomocysteine (AdoHcy) hydrolase (E.C. 3.3.1.1) isolated from bovine liver6 and Alcaleigenes faecalis.8 This enzyme, which catalyzes the reversible hydrolysis of AdoHcy to adenosine and homocysteine, is the only metabolic route for the removal of AdoHcy in eukaryotic cells.g Subsequently, inhibition of AdoHcy hydrolase by NpcA in eukaryotic cells (e.g., mouse L929 and neuroblastoma N2a cells) leads to elevation of cellular levels of AdoHcy and inhibition of S-adenosylmethionine (AdoMet) dependent methylations.lOJ1 The inhibition of AdoHcy hydrolase has been correlated with the antiviral activity of NpcA,l2 and (1) Hayashi, M.; Yuginuma, S.; Yoshioka, H.; Nakatsu, K. J . Antibiot. 1981, 34, 675.
(2) Yaginuma, S.; Muto, N.; Tsujino, M.; Sudate, Y.; Hayashi, M.; Otani, M. J. Antibiot. 1981, 34, 359. (3) Hayashi, M.; Yaginuma, S.; Muto, N.; Tsujino, N. Nucleic Acids Symp. Ser. 1980, 8, 65. (4) Yaginuma, S.; Tsujino, N.; Muto, N.; Fujii, T.; Hayano, K.; Matsuda, T.; Watanbe, T.; Abe, J. Current Chemotherapy and Infectious Disease, Proceedings of the 11th International Conference of Chemotherapy; Nelson, J. P., Grassi, C., Eds.; American Society for Microbiology: -. Washington, DC, 1980; Vol. 2, p 1559. (5) Tsujino, M.; Yaginuma, S.; Fujii, T.; Hagaso, K.; Matsuda, T.; Watanbe, T.: Abe, J. Current Chemotherapy and Infectious Disease, Proceedings of the 11th International Conference of Chemotherapy; Nelson, J. P., Grassi, C., Eds.; American Society for Microbiology: Washington, DC, 1980; Vol. 2, p 1558. (6) Borchardt, R. T.; Keller, B. T.; Patel-Thombre, U. J . Biol. Chem. 1984, 259, 4353. (7) De Clercq, E. Antimicrob. Agents Chernother. 1985, 28, 84. (8) Matuszewska, B.; Borchardt, R. T. Arch. Biochem. Biophys. 1987, 256, 50. (9) De la Haba, G.; Cantoni, G. L. J . Biol. Chern. 1959, 234, 603. (10) Keller, B. T.; Borchardt, R. T. Biological Methylation and Drug Design; Borchardt, R. T.; Creveling, C. R.; Ueland, P. M. Eds.; Humana: Clifton, NJ, 1986, p 385. (11) Ramakrishnan, V.; Borchardt, R. T. Neurochem. Int. 1987,10, 423. (12) De Clercq, E.; Cools, M. Biochem. Biophys. Res. Commun. 1985,129, 306.
0022-2623/88/1831-0500$01.50/00 1988 American Chemical Society
